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Re: Sharp MD glitch

Subject: Re: Sharp MD glitch
From: Klas Strandberg <>
Date: Mon, 22 Aug 2005 12:37:16 +0200
I wrote a posting about a year ago, about new Sharp MD's which had several 
strange errors. Input noise, among other things.

The cause is that the Plug In Power isn't provided by a common resistor 
(like 2,2kOhms to the + rail) but an integrated high impedance current 
generator.

When this current regulator runs unloaded, as will be the case when you 
connect a microphone with it's own power supply, - anything strange can 
happen.

Edirol R1 seems to have the same design and it even says in the manual that 
"the equipment can be damaged" if you use another mic than a Plug In Power 
one. They don't say if it is the Edirol or the mic that "can be damaged".

But the Edirol has a switch for "dynamic microphone" which probably cuts 
off the Plug In Power.
In real life, I have been using both Telingas and other non- plug in power 
mic's without problems, both with the switch in "condensor" and "dynamic" 
position.

I guess the relevant experimental design would be to connect the microphone 
to the Sharp via a condensor, but then also a resistor from the input to 
ground, allowing about 0,1 mA, simulating a microphone FET transistor. If 
that doesn't work, I would connect a FET transistor from the input to 
ground, with it's gate to ground. That would be the closest simulation of a 
Plug In Power microphone.


Klas.



At 05:05 2005-08-22, you wrote:
>Dan,
>I had a similar problem with my Sharp MD which you fixed with a piece
>of tape that isolated the metallic sleeve of the 1/8" mini connector
>from the metallicized case of the MD recorder.
>
>--greg
>
>
>--- In  Dan Dugan <> wrote:
> > Rob Danielson, you wrote,
> >
> > >In Len's critique of the M-Audio recorder's specs, he mentions the
> > >challenge of running the 48 volt phantom supply to the mics on such a
> > >low voltage. Some of the phantom supplies I tested with the NH-900
> > >had less noise when operating on higher voltage. Does the MD-MS722
> > >run on more voltage?
> >
> > It does, in fact. It has a 3.6V NiMh, which I suspect is a much
> > harder (lower impedance) voltage source than the 280's 1.5V alkaline.
> > But it could just as well be a shielding or power supply filtering
> > deficiency. We nature recordists are as demanding as classical music
> > recordists.
> >
> > >Sounds pretty pronounced if you're getting audible interruptions at
> > >record level 10.
> >
> > Level MIC L 12. Just barely audible fitzing mixed with the mic noise.
> > Quiet desert scene. Later takes (wind died down) at MIC L 17 had no
> > problem, so it wasn't a problem of coupling to the mic preamp (if
> > that were the case, it would get worse when gain was raised) but
> > probably in the A/D converter.
> >
> > -Dan
>
>
>
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>

Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email: 
         




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